Added note about launchMode on Android.

README.md

@@ -202,6 +202,12 @@ On Windows
 ren platforms\wp8\cordova\version.bat platforms\wp8\cordova\version
 ```
 
+### App restarts on Android after notification was clicked
+The launch mode for the main activity has to be set to `singleInstance`
+```xml
+<activity ... android:launchMode="singleInstance" ... />
+```
+
 ## Contributing
 
 1. Fork it